The present invention is directed to ultrasound transducers and their methods of manufacture and use.
In some applications of ultrasound transducers, such as high-intensity ultrasound therapeutic devices, the ultrasound transducers may have to meet certain criteria regarding the distribution of activity across the ultrasound transducer. For example, it may be desirable to provide acoustic or thermal uniformity across the proximate ultrasound transducer face as well as in the distal transducer's focal region. One reason for requiring acoustic or thermal uniformity proximately at the transducer face is that some of these devices also provide therapy in the nearfield and may have to avoid localized hot spots which can lead to overheating of nearfield tissue portions. Another reason to provide acoustic and thermal nearfield uniformity is that some ultrasound devices may utilize water-filled contact members which can undergo undesirable localized boiling if hot spots are present. Such considerations are in addition to the normal expectation of acoustic uniformity at the distal focus-which would lead to thermal-heating uniformity at that distal focus. As practitioners of the acoustic arts know, acoustic output nonuniformities on the proximate transducer face will also cause nonuniformities at the focus. Various examples of such devices are found in U.S. Pat. Nos. 6,840,936 and 6,805,129 which are hereby incorporated by reference.
The present invention is also directed to methods and devices for manufacturing ultrasound transducers and to methods for modifying the characteristics of an ultrasound transducer. The acceptance criteria regarding the distribution of activity across the ultrasound transducer nearfield, farfield or focal region typically require that some transducers be rejected. The present invention provides devices and methods for modifying transducers which might otherwise be rejected or might perform less than optimally. The present invention also allows for a substantial speedup in the process of determining whether such uniformity is acceptable or is a candidate for our additional and optional inventive uniformity-correction methods.